“On Holidays, I Forget Everything . . . Even My Ecological Footprint”: Sustainable Tourism through Daily Practices or Compartmentalisation as a Keyword?

: In today’s struggle against climate change and for less dependence on fossil fuels, why do people who adopt practices with a lower impact on the environment forget them during their holidays? This contribution sheds new light on sustainable tourism by focusing on daily practices during holidays. Based on the concrete practices of holidaymakers, this contribution proposes to understand some factors and contexts favouring the persistence, the transformation or the abandonment of sustainable practice(s) during holidays. The theoretical framework of this research mainly draws on social practice theories. The empirical material is made of 38 biographical in-depth and crossed interviews: twenty on daily practices with young adults (25–35 years old) who have adopted at least one more sustainable daily practice and who went on holidays for the past year reinforced by 18 interviews with some of their parents.


Introduction
Alternative consumption is of growing interest in today's society and every area seems to be affected. Eating local products, saving energy, wearing second hand clothes, and shopping in bulk have become fashionable and encourage new forms of practices. Tourism is not to be outdone. With the rise of this new way of consuming and travelling, the adoption of practices with a lower impact on the environment could be considered as a homogeneous and common phenomenon. The purpose of this article is to show that it is not the case, as demonstrated by comparing practices in the everyday life and practices during holidays. Do the more sustainable practices adopted during daily life persist during touristic holidays? How and why?
For the last twenty years or so, there is an abundant scientific literature on sustainable consumption [1][2][3][4] and "green" tourism [5][6][7]. Nevertheless, over the last decade, these first waves of research have been widely criticized [8][9][10][11][12][13], particularly because they systematically consider that the individual is the main driver of change. This article is part of this critical movement in applying social practice theories [14,15] as a theoretical framework.
The second special feature of this article is that it develops a theme that is not yet well explored, namely the persistence of sustainable practices during holidays. Indeed, while there is research on the relationship between tourism and the ecological footprint [16][17][18], or between tourism and transport use [19][20][21] and still other studies on sustainable tourism practices [22][23][24][25], there is very little research linking home-based and tourism-based sustainable practices [10,26].
The originality of this article is therefore to observe sustainable tourism through the daily practices adopted by holidaymakers. The approach of this article is to consider holidays as a period delimited in time in order to compare (un)sustainable practices adopted on holidays with those of everyday life in two areas: mobility and food. Since the focus is on tourists' practices, this article may be of interest to tourism professionals so that they could better understand their customers' levers and barriers about maintaining sustainable practices even while they travel.
To this end, this paper adopts an innovative theoretical framework based on theories of social practices. Data are collected through twenty in-depth interviews with young adults (25-35 years old) from all of the French-speaking provinces of Belgium. These interviews were crossed with those of some parents of these young adults in order to reinforce the quality and veracity of the information obtained. After a theoretical framing on sustainable consumption, tourism, and practices, the presentation of results is divided into two distinct parts: the first answers the titular question by a descriptive comparison between the practices of daily life and those adopted during holidays, and the second attempts to identify some avenues for better highlighting some distinct dimensions of these practices.

Theoretical Framework
The theoretical part of this article focuses successively on sustainable consumption, tourism, and social practices. Each term will be defined and the position of this article in relation to each topic is explained.

Sustainable Consumption
In June 1992, the Earth Summit took place in Rio de Janeiro. In line with the Brundtland Report published in 1987 [27], 179 head of states took the decision to address sustainable development issues. It is on this occasion that the terminology "sustainable consumption" appears for the first time on the international political agenda [28,29]. In 1994, at a round table during the Oslo Symposium on Sustainable Consumption, the Norwegian Ministry of the Environment proposes this working definition of sustainable consumption and production: "The use of services and related products, which respond to basic needs and bring a better quality of life while minimising the use of natural resources and toxic materials as well as the emissions of waste and pollutants over the life cycle of the service or product so as not to jeopardise the needs of future generations" [30].
While this definition is regularly criticized (in particular because it combines the concepts of sustainable production and sustainable consumption in the same definition), it must be noted that no other definition has so far been unanimously accepted. Moreover, other criticisms, including those of Latouche [31,32], also highlight the fact that "consumption that is called critical, responsible, or ethical and Fair Trade can appear to be oxymorons on a par with sustainable development. The need to free ourselves from consumerism is as great as, if not greater than, that of putting an end to developmentism. Slogans such as 'consume ethically' and consumption in a 'de-growth' perspective 'buy fair' are contradictory and perverse, for they conserve the core problem, i.e., the consumption imperative" [32] (p. 181).
While it is difficult if at all possible to define what sustainable development is, it is equally complicated to define what sustainable practices are. Indeed, outlining the exhaustive limits of what exactly a "green" practice is a complex exercise that has not yet been achieved in the current literature. The core of the problem is that defining the "sustainability" feature is a combination of environmental, technological, social, ethical, and philosophical dimensions that are difficult to delimit. As an example, taking the train to go to work could be considered a sustainable practice. Nevertheless, taking the train implies favoring nuclear energy over fossil energy (at least in Belgium), which may be questionable given the risks (environmental and human) associated with nuclear power plants. On the other hand, taking the train is considered a "green" practice, especially if it replaces the car because it limits global warming. However, is it still a "green" practice if the bike is abandoned in favor of the train?
In the context of this article, "green" practices are what is commonly accepted as such by public opinion (e.g., using public transport, reducing daily meat consumption) without implying that "green" practice refers to a necessary environmental motivation behind the practice [33].

Tourism and Sustainable Tourism
As in other Western societies [34,35], Belgian touristic demand has been growing every year since 1945. At the same time, deeper attention to sustainable tourism seem to be making a real breakthrough in the area over the last years. The United Nation World Tourism Organization (UNWTO) defines sustainable tourism as "tourism activities that can be maintained, or sustained, indefinitely in their social, economic, cultural and environmental contexts" [35] (p. 1). This concept has led to an impressive literature: the International Centre for Tourist Research and Studies (CIRET) [36] lists no less than 150,000 tourism-related items, including around 5000 dealing specifically with sustainable tourism.
According to Buckley [37], who conducted an extensive state-of-the-art review on the subject, studies on sustainable tourism issues are divided into two phases. The first appeared at the end of the 1980s and was mainly carried out by geographers. These works were based on the assumption that "sustainable development is inherently good and appropriate for tourism, and that its adoption will solve many of the negative problems that have resulted from the development of tourism" [17] (p. 8). The second period comes ten years later and is mainly based on the criticism of this concept [11][12][13]38,39].
In addition, many sociologists also draw attention to the fact that framing of sustainable tourism is also being taken over by social psychologists and social marketers who are developing theories that emphasize individual will and responsibility [34,40]. Hall [33] reviews different approaches to studying the adoption of sustainable holiday practices and concludes that: "without facing up to the implications of structure and institutions then the likelihood of tourism activities and behaviours being "locked-in" to particular unsustainable socio-technical systems of provision is greatly increased" [34] (p. 1103).
This article is part of this critical trend as it proposes to analyze sustainable tourism through the persistence or non-persistence of sustainable daily practices during the holidays.

Studying Sustainable Behaviours vs. Sustainable Practices
The popularization of the concept of sustainable development leads to various initiatives, declarations and watchwords [41], political and private companies decisions [42,43], and activist movements [44,45]. The main objective of these initiatives was to "expect consumers to exert a significant favourable influence [on the environment]" [41] (p. 1). Indeed, according to Shove and Spurling, "[i]n popular and policy discourses, it is usual to explain such changes as outcomes of individual choices" [46].
Moreover, in the academic sphere, social psychologists and economists took up the field of sustainable consumption [9] and mainly used the rational action paradigm [1,2] based on individuals and behaviours. These reflections lead to the creation of different "green" consumer behaviours [3,4,47] based on variables such as environmental values, education or personal motivations [48]. These psychosocial theories have two points in common: the unit of analysis is systematically the individual and the basic premise is that "moving towards a more sustainable society depends on helping people to make better choice" [46] (p. 1). From this point of view, the adoption of sustainable practice therefore depends only on an individual's willingness to change. Sociologist E. Shove [8] ironically reinvests the ABC (Attitudes, Behaviour, Context) model developed by P. Stern by changing the "Context" by "Choices." She explains that the intervention strategies put in place for the adoption of sustainable behaviours are based on a presupposition that considers "that environmental damage is a consequence of individual action and that given better information or more appropriate incentives damaging individuals could choose to act more responsibly and could choose to adopt "pro-environmental behaviours" [8] (p. 1275).
Nevertheless, over the past two decades or so, consumption theories have experienced a "practice turn" [49] in the sense that "attention has turned from individual consumers to the cultural, material and economic structuring of consumption" [46] (p. 3). By shifting the focus from behaviours to practices, theories of social practices "provides some new insights into how consumption is organized and how it might best be analysed" [50] (p. 132).

Social Practices Theories
Following this line of thought, the theoretical framework of this article is based on the theories of social practices. This stream of thought was initially inspired by the philosophy of Wittgenstein, the sociology of Bourdieu, Giddens' theory of structuration [51] but also by scientific concepts from the area of science and technology [52]. These theoretical frameworks do not constitute a corpus of homogeneous contributions but represent "a multiple theory that commonly adopts a conceptual position towards culturally oriented research" [53] (p. 638).
Concerning the definition of the practice, most authors of this theoretical stream agree on the two definitions given by Schatzki that define practice as a performance and as "a temporally unfolding and spatially dispersed nexus of doings and sayings" [14] (p. 89). For Schatzki, practice as performance refers to "the doing, the actual activity or energization, at the heart of action. (...) It designates the continuous happening at the core of human life, which is one of the most important features of the world" [14] (p. 90). To exist, a practice therefore must be performed, in other words, translated into concrete action. From the second definition of a practice, Schatzki lists various components that make up a practice: know-how and routines, institutionalized procedures and teleoaffective structures. Reckwitz [15] adds a fourth component, technologies and physical structures. The components are therefore constitutive of a practice.
A major characteristic of this framework is that the practice becomes the unit of social analysis. The objective of these theories is indeed to "put the practice in the foreground and therefore the individual in the background" [54] (p. 22). Therefore, it is no longer the individual who adopts a practice, but the practice itself that recruits the individual. The individual is also called "practitioner" [14] and is therefore the "carrier" of the practice in the sense that he constitutes "the unique crossing point of practices, of bodily-mental routines" [15] (p. 256). In this way, practices do not necessarily appear homogeneous, either among themselves nor among the different practice carriers. This line of thought will be applied empirically in the first section of the results below.
Warde [55] distinguishes two successive waves in social practices theories. The first generation lays the foundations of this framework and is invested by various theorists of the twentieth century (Bourdieu [56], Foucault, Giddens, de Certeau, . . . ). The initial objective of the first wave was to overcome the traditional dualism between structure (holist vision) and actor (individualistic vision) [50]. This willingness to reconcile the holistic view with the individualist is originally articulated by A. Giddens who states that "the basic domain of study of social science, according to the theory of structuration, is neither the experience of individual actor, nor the existence of any form of societal totality, but social practices ordered across space and time" [57] (p. 2).
The second generation aims to test and deepen the theoretical concepts established by the first wave of theorists. Therefore, they have aimed to abandon a static vision of the practice that would manifest in an individual, either passive and undergoing structural dictates, or totally self-determined. To do this, they focus on the practices as such and consider that they are "structured and organized through three dimensions: practical understanding; explicit rules; and teleoaffectivity " [58] (p. 300). These different dimensions inspire the analysis of the second part of the results' section.

Data and Methods
The following presentation is based on Tong's article of [59] that provides a set of 32 items to be explained how reporting on a qualitative research. Data were collected in Belgium as explained below.

Data
The qualitative method used in this research is the in-depth interview, defined by Boyce and Neale as a "qualitative research technique that involves conducting intensive individual interviews with a small number of respondents to explore their perspectives on a particular idea, program, or situation" [60]. My objective was to obtain a narrative of practices in the sense of Bertaux [61], that is to say a set of in-depth and meticulous descriptions of personal experiences as far back the interviewees could remember.
The topics of these interviews include the following: practices related to food, to shopping for grocery and clothes, as well as practices related to mobility. The 'history' of these practices was searched for by the researcher with each participant.
This research includes 36 in-depth interviews: 20 in-depth interviews with young adults reinforced by 16 in-depth interviews with some of their parents. In this article, only the practices of young adults will be studied, but all the interviews will be considered. These cross-interviews on two generations [62,63] as well as between siblings are interesting because they solidify the quality of the data collected individually while providing key information for understanding family dynamics and the construction and evolution of consumption practices. I conducted the face-to-face interviews from September to November 2018 in all the provinces of French-speaking Belgium. I always met the interviewees at their home.
I interviewed 22 young adults, of whom 20 went on holiday during the last year and are therefore included in this study. All the young adults interviewed are between 24 and 36 years old and were born between 1982 and 1994. These generations are very relevant because they were born with the issues of sustainable development and environmental protection. This age group is also one experiencing many changes: entering the labour market, leaving their parents' home, having children, and so forth. The situations specific to this period of life can also encourage or hinder the adoption of practices with a lower impact on the environment. Indeed, it is during this transition period that young adults adopt their first real consumption practices. For example, how and with what to fill the fridge? Where to go for groceries? How to get there? Which products to buy? Where and how to go on holiday? How to get around on a daily basis? As long as they live with their parents, they are always dependent on them.
The young adults have been selected on three common characteristics: they have all left their parents' family home; they have all adopted in their daily lives at least one practice presumed to have a lower impact on the environment; they all have at least one parent who was available for an interview. Among these young adults, three are only children, three are couples, and in two cases both of two siblings were interviewed. They are also young people with a relatively high socioeconomic level and belonging to the upper-middle social class. Twenty out of 22 have a higher degree (POA or Master's degree). It can therefore be assumed that financial resources are rather homogenous within the sample. Sociodemographic data of the young adults are provided in the Appendix A (Table A1). To preserve anonymity, all first names have been changed.
The interviewees were recruited from different channels: by sending emails to managers of local transition initiatives linked with sustainable consumption (such as groups buying local, organic and seasonal food products; Repair Cafés; etc.) and by attending events about sustainable practices (such as conferences on zero waste or vegetarianism). The particularity of the presentation of the research to the respondents is to be highlighted, as the initial topic announced did not mention reflexion on the sustainability dimension of the practice. Respondents were told that the work focused on the transmission of habits across generations. The aim of this approach was to try to avoid social desirability bias [64] that would encourage a consciously or unconsciously "greening" of practices by respondents.
Regarding interviews with parents, the recruitment process is obviously different. I asked for their contact information once I had finished the interview with the young adults. The interview with the parents usually took place a few weeks after their children's interview. Even if the topics remained the same, the interview grids were enriched on a case-by-case basis according to the interviews of their children previously recorded. For example, if a young adult had related an interesting situation to me, I would be careful to have his/her parent(s) tell it to me as well. This allowed me to clarify some of the data but also to obtain a reinforcement and a new perspective on the data already collected.
The analysis below focuses on mobility and food practices compared in two different periods: in everyday life and during the holidays. Concerning holidays, only leisure tourism was considered. In other words, business travel was systematically excluded from the data used in this contribution. In addition, only stays of three nights or more were taken into consideration. The interests concerning daily living practices were similar to those during the holiday period. The objective was to obtain the most detailed description for each practice studied.

Method
All interviews were recorded before being entirely transcribed and custom-coded using the qualitative analysis software NVivo. The coding made it possible to obtain cross-tabulated information between the different practices (related to food and mobility), the different age groups (young adults and their parents) and the different periods analysed (daily life and holidays).
Using Kaufmann's approach [64], an in-depth vertical analysis was carried out for each interview in order to prepare to trace the career of each practice described by the young adults. The parents' interview reinforced the data previously collected by providing new insights into certain situations. This first step was followed by an overall horizontal analysis that revealed some recurrences and other trends that are explained in the Results section of this article just below.
Without claiming that these results may be exhaustive in any way (due to the number of observations and the limited number of the participants), the data collected by the in-depth interviews and consolidated by the cross-interviews provide numerous information that is to be processed. The results presented below are based on two ways of processing the data from these in-depth interviews: first, a more quantitative-oriented approach to observe certain interesting trends regarding mobility practices, second, content analyses to describe in detail food and grocery practices.

Results
The first section compares daily living practices in the categories of mobility and food with those adopted during holidays in order to see whether sustainable daily practices persist during the holidays. From these results, the second section analyses each component of the practice in order to highlight its impact on the adoption of sustainable practices.

Which Holiday Destination and Which Mean of Transport?
Out of the 22 young adults, 20 went on holidays during the last year. The destinations were the following ones: Belgium for one out of the twenty, France for eight, other Europeans countries (Denmark, Norway, Italy, The Netherlands and Spain for two of them [who are not in a relationship together]) for six others and non-European countries for the last five (Malaysia, Columbia, Indonesia and Costa Rica for two of them [who are in a relationship together]) ( Table 1). Regarding the means of transport to reach their destination, ten took a plane: four to reach a non-European destination, five to reach a European country other than France, and one to reach France. The other ten used a car: mainly to go to France (this is the case for eight of them, including one who carpooled with friends), one to go to the Belgian coast and one who hitchhiked to Denmark. These trends corroborate these observed by Eurostat [65] the official European statistics website: France is the favourite tourist destination of Belgians and flying is the most popular for stays of more than four nights. Table 2 allows having a look at the daily mode of transportation (rows) in relation to the mode of transportation adopted to travel to the holiday destination (columns). As for the nine adults who use a car as a main daily means of transportation, six of them flew: three of them to a non-European destination and three of them to a European destination (one of whom was flying to France). The other three took a car, one of which was a carpool. Out of the 11 people who use public transport on a daily basis, 10 went on holiday. Three took the plane (two of them to a non-European destination while the remaining one went to Spain), and six others took a car to go to France, the Netherlands, or stay in Belgium.
These results are interesting in the sense that it appears there is no apparent persistence (or continuity) between daily practice and the mode of reaching the holiday destination. Moreover, it seems that the means of transport adopted to reach the holiday destination is, in most cases, "less sustainable" than the transport used on a daily basis. Indeed, six out of nine daily drivers flew, while six out of ten daily users of public transport mainly used a car for their travel.

On-Site Mobility: By Car
Regarding holiday mobility, once on-site, there is an obvious heterogeneity between the observed practices. First, everything depends on the means of transport used to get there (Table 3). Indeed, generally those who have travelled by car continue to use it during their stay. Only one exemption is observed: a woman traded her car for a bike once at her holiday spot (she went to the Netherlands). Table 3. Transport to reach the holiday destination (rows) vs. transport on-site (columns). For those who arrived by plane, mobility at the holiday destination is performed either by car rental or by use of public transport. Of those who opted for public transport once they landed, half do not have a driving license, therefore excluding use of the car. Those who went on holidays in non-European countries rent a car more easily.

Public transport
Finally, Table 4 compares the daily means of transport (rows) with those used at holiday sites (columns). Car use represents half of the answers. Out of the nine who use a car as their main means of transport on a daily basis, five also adopt it to travel on holiday. Out of the ten who use public transport on a daily basis, half also opted for a car. Nevertheless, this comparison presents the highest homogeneity in the persistence of daily practices during the holidays: most people who drive a car daily also use a car for mobility once at their holiday destination. These comparisons between home-based and tourism-based practices do not pretend to be exhaustive but draw attention to certain main trends. It can therefore be seen that with regard to mobility, the adoption of sustainable holiday practices takes place in a heterogeneous way, without necessarily corresponding to the sustainable practices adopted in daily life.

Eating and Grocery Shopping
Concerning the comparison between food in everyday life and food on holiday, four aspects evoked during the interviews are analysed: whether or not to follow a vegetarian diet, whether to eat local products, whether or not to eat organic products, whether to source or not bulk products.
Of the 20 young adults studied here, five are vegetarians in daily life, of whom three said they had eaten meat and/or fish during their holiday: "Well, when we're on vacation with our parents, we eat a little organic and fair trade fish. We're taking it upon ourselves. You see, I think you have to stay grounded in your own family". (Madeleine, F., 26-year-old, in couple without children, public transport user and vegetarian in daily life). Sometimes, the acknowledgment does not come from the person concerned but from his or her relatives as Clara about her partner: "Actually, my boyfriend doesn't eat meat at home, but he could eat meat when he goes out, or on vacation... for example if we go once to a restaurant. On vacation, let's just say it happens a little more often" (Clara, F., 25-year-old, without children, car driver and vegetarian) or Lise (F., 51-year-old) about her daughter and her son-in-law: "Yes, they had started by avoiding meat and fish but in fact, on holidays, they could eat some fish...even chicken." These first quotes already provide an insight into the role of relatives in the persistence of sustainable daily practices during holidays.
Seven young adults (including one vegetarian) reported that they use bulk supplies in their daily lives. However, only one mentioned it when it came to holiday food. Not mentioning bulk does not mean that no one buys bulk during the holidays. Nevertheless, this marks a difference between daily consumption where bulk is mentioned spontaneously and holiday food where almost no one refers to it. In addition, the only time bulk products are discussed during the holidays is to show how difficult this practice is.
"I'm trying to buy only bulk and not go to the supermarket anymore! But for example, when you go on a hike, I have to make a compromise. When we're on a hike, we're trying to lighten up so I bought soup bags in a supermarket. And while I was there, I bought some pasta.... It is still local pasta but it is plastic wrapped. Then I also bought chocolate, because bulk chocolate is really very expensive... It's the same for dried fruit: it's single or double [the price]! When I buy things for the group, I don't dare to buy everything in bulk." (Lola, F., 30-year-old, in couple, without child, bulk consumer in daily life).
This quotation highlights again that sustainable practices of daily life are not especially transferred during holidays. But this quote also shows the influence of relatives and of friends in adopting practices and the compromises that must be made.
Concerning the other two criteria (local food and organic food), the analysis proved to be more complicated because these are assimilated as systematically linked for some respondents; however, these links are not necessarily valid. As a result, most of the interviews focus on local food on holiday but few address the organic characteristic of their food. Jean-Baptiste's quotation clearly shows that conflation is quickly achieved: "At home, we eat only local and organic food. So, on holidays, food is basically the same as what we do here. We go grocery shopping, we eat local, we try to find local products." (Jean-Baptiste, M., local and organic food consumer in daily life). Finally, when the discussion came to local and organic food, it was essentially to demonstrate the complexity of getting it on holiday as Liliane says, "It is true that on a daily basis, eating organic food is one of my priorities. On the other hand, on holiday, clearly I am less attentive.... Actually, I don't know all the available options and I'm going to keep it simple" (Liliane, F., 32-year-old, local and organic food consumer in daily life).
Another recurrent conflation was to confuse locally produced food and local food specialities as Alix does: "I eat local food home and away. For example, in Asian countries, I eat the typical dish. I'm not going to a French restaurant while I'm in India. I prefer to eat local!" (Alix, F., 26-year-old, became vegetarian after her three-month trip in Malaysia). There is no guarantee that the typical dish will be cooked with local products but Alix seems to think so.
Concerning food, it is clear once again that the adoption of more sustainable practices during holidays does not take place in the same way as in everyday life. Here too, it seems difficult to observe recurrences or homogeneity across the various interviews, but it must be noted that more the sustainable practices adopted in everyday life are not systematically transferred to holidays. Except for daily mobility versus holiday on-site mobility, there is little consistency between sustainable practices during periods of tourism versus everyday.

Understanding Compartmentalisation Through the Lenses of Social Practice Theories
Based on the three components of practice defined by Schatzki [14] as well as the one added by Reckwitz [15], this second part of the article attempts to better understand the reasons for variations observed between the adoption of sustainable practices in daily life and on holidays. This section provides an opportunity to empirically apply the conceptual framework of social practices theories by starting once again from the practices related to the means of transport used to reach the holiday destination, to mobility on-site, and then to eating and grocery shopping. The last subsection highlights some dimensions that are not yet (or very seldom) taken into account by these theories.

Material Structures: Planning a Trip without Leaving One's Sofa
Today, a set of material arrangements (such as low-cost airlines, online accommodation booking platforms, travel agencies, etc.) allow planning for tailor-made, fast and cheap holidays. These new structures correspond to material structures and are defined as "objects, infrastructures, tools, hardware and the body itself" [66]. Material structures are essential to the realization of any practice since they are the concrete "equipment" necessary for the realization of the practice. This quote of Nathan clearly illustrates this dimension: "I wanted to go to Spain and I was really sick of everything, so I booked it in two minutes: fast and efficient from my couch. I packed my backpack, took a plane and found myself in northern Spain without really knowing where I was going." (Nathan, M., 32-year-old, vegetarian and car-driver in daily life) Indeed, it is nowadays possible to plan a trip without leaving one's sofa. Regularly, new material structures appear (e.g., the Airbnb platform, which now allows renting a room or entire accommodation in any city of the world) to facilitate tourism. These material structures obviously encourage going on holidays, making the various planning and booking processes much more accessible and further, encouraging destinations beyond the country's borders.
Sustainable tourism is no exception. Nevertheless, even if sustainable tourism offers are increasingly developing, it is still not enough to allow systematically the adoption of practices with a lower impact on the environment. Indeed, sustainable alternatives are sometimes lacking or are too expensive, impending the adoption of sustainable practice during holidays as Caroline explains "If I had more money, I would go on holiday by train rather than by plane, I think! But flying is easy, it's cheap. When I'll be rich and famous, I'll take the train!" (Caroline, F., 28-year-old, cyclist in daily life). These material structures can also be mobilized to justify the non-adoption of sustainable practice, as is the case in the two quotations above. Michel uses the lack of material structures as an excuse. He considers that material structures do not allow him to travel in any other way: "We do not like all-inclusive hotels, but sometimes we have no choice but to go there" (Michel, M., 35-year-old, car-driver and vegetarian in daily life). According to him, he is "forced" to adopt an unsustainable practice because of the limited offers. These contradicts the ABC psychology model and is therefore in line with Shove's approach [8] who demonstrates that the adoption of sustainable practices is not only a matter of personal willingness to change. Nevertheless, it seems that the desire to go on vacation outweighs ecological considerations. At no time does Michel question going on holiday. This observation also corroborates [10] who says that people who are aware about the impact of their practices on the environment are "not actually willing to reduce their flying habits significantly" (p. 480).
Therefore, it can be concluded that the lack of a sustainable material structure does not prevent people from going on holiday, even for environmentally sensitive individuals. If a sustainable option can be found among the material structures, so much the better for them, if not, never mind.

A Matter of Habit
Out of these 22 young adults, 20 said they went on holidays annually when they lived with their parents. Therefore, all the stories of practices report annual holidays, and this as far back as they can go back in the narration. Indeed, when the question of holidays during childhood is asked, all informants could describe certain family routines, such as Alix Luc and Aude.
"During the family holidays ... We never went to a hotel, it was always camping. It was in Spain or in South of France. We went once to Turkey, to the hotel. This is the year my dad sold some land, so we had a little more money (she laughs). But it has never been a luxury vacation." (Alix, F., 26-year-old, vegetarian, public transport user in daily life, went to Malaysia last year).
"With my parents, it was always the North Sea ... because my mother is extremely scared of the plane. I think she does not like the train too much, nor the boat . . . ( . . . ). And then, we went 2-3 weeks a year to the North Sea. I would say that we went maximum three times elsewhere, that is to say: in France." (Lucas, M., 29-year-old, vegetarian, car-driver in daily life, went to the North Sea last year).
"Every year, since I was as young as I remember, we always went to the mountains with my parents during the summer. The tradition stopped last year as Coralie and I, and our boyfriends, are working, so it was difficult to coordinate everyone." (Maud, F., 26-year-old, vegetarian, public transport user in daily life, went to France last year).
If the destinations are less exotic than those described previously (perhaps namely because all the tools facilitating accessibility for far away destinations did not exist and/or were much more expensive at the time), these quotes show the regularity that these young adults experienced in their childhood vacations: each year they left with their family during the summer. Once adults, they reclaim this practice (choosing nevertheless more exotic destinations) but continue the tradition. The routines adopted beginning in childhood continue to adulthood even if they are updated. It is therefore a deep anchoring and this observation testifies to the routine nature of a practice [14] while highlighting the difficulty in changing practices.

Teleoaffective Structures: Between Social Distinction and Guilt
Another of the main components of the practice is the teleoaffective structure that Schatzki [14] defines as "embracing ends, projects, tasks, purposes, beliefs, emotions and moods" (p. 89). The justifications given by young adults are part of teleoaffective structures. In a spirit of synthesis, only two dimensions are addressed in this section. The first one concerns the symbolic importance of holidays, especially concerning which holiday destinations and the means of transport used to get there. The second dimension deals with feelings of guilt about holidays. Why does going on holidays remain non-negotiable while the guilt of leaving is sometimes heavy to bear individually?
The two quotations below show indeed the existing societal standard for the holiday area. Indeed, Lucas clearly justify his type of vacation by implying that some are better than others: "As I have more money, my life stabilizes; I make sexier trips ... Like Tuscany, Southern Spain, and South of France, places where I was not especially before ... and I also did City trips to Paris, London, and Amsterdam." (Lucas, M., 28-year-old, vegetarian in daily life).
Mégane's quote goes in the same direction when she explains this: "I went for a month in Peru. The year after, I went to Nicaragua . . . That's the way it is: I like to go to the South, generally. But last year ... You know, with the opening of the store [hers], I could not make big follies. So we just went to the South of France with a caravan." (Mégane, F., 27-year-old, public transport driver in daily life) Here, Mégane's quote is enlightening. While at the beginning of the interview, she explained how practical it was to travel in a caravan, she nevertheless admits later that this style of vacation is a default option because of a lack of financial resources. She also implied that if she had had the opportunity, she would have gone to another destination.
These quotes show the gradation between the different destinations and means of transport: travelling to the North Sea or the South of France by caravan does not mean the same thing as going to Peru or Nicaragua by plane. This may reflect the importance of holidays in the current social system and the role of holidays in identifying with a social class. That is what Crick says: "the world of tourism is rife with the class distinction in our everyday world" [67] (p. 334). In this sense, holidays could be seen as a form of ostentatious consumption in the sense of Veblen [68]. Moreover, the two young adults of the sample who did not go on holiday during the last year are two women who have a slightly lower socio-economic level compared to the rest of the sample. These reflections emphasize the importance of social classes according to the holiday style adopted.
While holidays are socially normalized [69] and routinized in the daily lives of the rather well-off young adults, some feel a strong sense of guilt. Indeed holidays can be seen as a parenthesis of pleasure often avoided in daily routines sometimes strict, but still a source of guilty for young adults who have internalized environmental issues. Nevertheless, it is also interesting to note that just because guilt is present individually, it does not mean that the practices that have the greatest impact on the environment cease as Aude's testimony shows: "We know that flying is not good for environment, but we still do it: we need it too much!"(Aude, F., 35-year-old, practicing voluntary simplicity) or the quotes of Camille and Alix: "I love spending Christmas in the mountains [that means at least 700 km away from her place] because I love the spirit that prevails there. But at the same time, I feel quite guilty because I succumb to a commercial trend... Lights, gifts, packaging, ice rink... I'm participating in a huge ecological disaster!" (Camille, F., 24-year-old, went to Norway by plane last summer) "When you fly over Malaysia, you only see palm fields, and already you think it's a problem. Then you land and you see the pollution of the sea and then you think about biodiversity, nature, animals. You see the streets filled with dirt, and garbage. I was just obsessing about it, and I felt so bad... I was so shocked. And at the same time I felt responsible and helpless." (Alix, F., 26-year-old, became vegetarian after her three-month trip in Malaysia).
Here, these quote show that responsibility is individualized, placed on the shoulders of each individual. This gives the impression that climate and environmental issues are a set of problems that can be solved personally rather than as a global problem beyond the individual level. These results corroborate Barr who explains that over the last 20-25 years, a fundamental shift has occurred in environmental issues: "policy has begun to shift from a 'top-down' approach to a 'bottom-up'" one [70] (p. 51). As Barr explains it, initially ecological problems were discussed on a macro scale such as related to governments and major organisations. However "in recent years, there has been a growing emphasis on the role of individual consumers and their potential to mitigate against global, as well as local, environmental problems" [10] (p. 474).
Therefore, the adoption of a sustainable practice does not result solely from an individual's desire for change. Good will is not enough to green everyday practices. Holidaymakers are aware of the impact of their practices on the environment, some even feel guilty, yet they continue to leave. These results corroborate Shove [69] saying that "the vast majority of environmentally significant consumption is not a matter of individual choice, green or otherwise. It is instead bound with, and constitutive of, irredeemably social practices governed by norms like respectability, appropriateness, competence and excellence" (p. 198).

"Thinking Globally, Acting Locally": The Focus of Institutionalized Procedures on Individual Practices
The fourth component of a practice is institutionalized procedures which refer to "the structural properties involv[ing] elements of meaning and communication, control and power relations, and legitimacy" [71] (p. 2491). Some institutionalized procedures could also have an influence on whether or not sustainable practices are adopted during holidays. So, the non-taxation of kerosene by European countries and paid holidays just before summer holidays (in Belgium) are two elements of institutionalised procedures.
First, a leaked report commissioned by the European Commission finds that the European aviation sector is chronically undertaxed relative to other aviation markets and other means of transport. The report was completed last year. It has not yet been made public but has been distributed by the NGO Transport & Environment. The report focused on three different forms of taxation: a tax on the ticket purchased by the passenger, value added tax (VAT) on the same ticket, and the tax on kerosene which is used for jet fuel. For now, no European member country applies a tax on kerosene, while other countries such as the United States, Japan or Canada do (1 cent, 14 cents and 8 cents/litre, respectively). VAT was defined at 0% by an EU directive (2006/112/EC) but this did not prevent several countries from applying VAT, from 6% in Portugal to 25% in Croatia. By the way, seven Member States apply taxes on kerosene at an average of €11 per ticket. By comparison, Australia, Brazil or Mexico apply a tax on kerosene of around €30-40 per airline ticket [72]. Such state decisions are likely to influence whether or not practices with a lower environmental impact are adopted.
Moreover, people working full time in Belgium generally benefit from four week of holidays. During these holidays, employees continue to receive their salaries. In addition, between May and June, they receive a double holiday allowance based on their last working year [73]. This nest egg may probably be an additional incentive (or even a legitimization?) to take a vacation.
However, this information must be taken with some caution because none of the twenty interviewees mentioned these dimensions explicitly. The influence of material structures therefore seems to be the least empirically testable component of a practice. But this doesn't diminish its possible impact of the adoption, transformation or abandonment of sustainable practices during holidays.

Holidays with Children and Partners: The Role of the Relatives
This last topic is rarely mentioned in research using social practices theories. Indeed, Bartiaux and Reátegui Salmón [26] claim that "these theories do not provide an explicit place [for] social interactions" (p. 206). Beyond these two authors, no others using this theoretical framework seem to consider that the carrier of a practice is intertwined in a family and social fabric. In this sense, this section argues that relatives also play a role in the recruiting or not of practices with a lower impact on the environment as compromises must be made with the different family members.
First, all the young adults with children interviewed went on holiday last year. Nevertheless, having or not child(ren) seems to be one of the factors determining the destination and the means of transport. Indeed, among the eight young adults who went to France, five are parents with children aged 4 or younger. The only parents who did not go to France went to Costa Rica but their children are older (6 and 8 years old).
Among these five parents who went to France, three claimed to have chosen France because of their young children. They explained that their previous trips (before the birth of the children) were more exotic but that they had recently went for France for practical reasons.
"Before being in my thirties, I travelled a lot. It was something that really meant a lot to me. I went to Finland, Australia, India, the Reunion Island, and I regularly did city-trips. Then I settled down, we had a baby and we're becoming more reasonable." (Elodie, F., 34-year-old, mother of a 15-month-old baby) "We did Cuba, Namibia, Australia, Indonesia, Laos, and Thailand... And we did one or two city-trips per year: Stockholm, Berlin, Prague, Lisbon, Porto... Now, for the past two years, we've changed our habits because of the little chip...We are going much closer. This year, it was exclusively France." (Louise, F., 32-year-old, mother of a 14-month-old baby) "And then I got a taste for holidays in the South and everything... But this year, since we have the baby and he's a little annoying, and he doesn't sleep through the night, etc., we went to the North Sea [in Belgium]!" (Lucas, M., 28-year-old, father of a 2-year-old baby). So, having children or not seems to be a key factor concerning the holiday destination. Indeed, while young parents in this sample have always travelled and continue to do so once they have children, their destinations are changing according to their new constraints. Having children can also determine the means of transport to reach the destination and/or to move on-site.
"It's much easier to go by car and stay by car with the little one. We thought we were going to go back to the sun, but when you do the counting, the plane with the stroller, the bags, the stuff, arriving with nothing, renting a car... Forget about it. Forget about it. It's not a vacation anymore, is it?" (Etienne, M., 29-year-old, father of a 14-month-old baby) In the same way, some young adults reported that they take advantage of being childless to make long trips as Michelle: "I like to go far away. My starting-point is that as long as you do not have children, you have to take advantage of it." (Michelle, F., 27-year-old, in couple without children). However, Michelle's case show compromises. Indeed, since she met her partner, she has changed her on-site mobility during her holidays.
"But it's true that I love going far away, discovering a new language, a new culture, different food, feeling a little globe-trotting in my soul, with my backpack, having to take the bus... or whatever. Well, when I started dating [name of her partner], we found compromises because he wasn't into taking the bus. So, instead of taking the bus, we rent cars." (Michelle, F., 27-year-old, in couple without children and car driver in daily life).
As pointed by Hall [34] "people do not act as isolated individuals" (p. 1099). These observations highlight a limitation of social practice theories: that they take too little into account the role of relatives in the adoption, transformation, persistence of abandonment of sustainable practices. However, these relatives, whether children or companions, seem to have a significant influence on the destination or modes of travel, as the above quotes show. Only the fact of going on holiday does not seem to be questioned by relatives.

Conclusions
On methodological grounds, while the data used in this article cannot claim either saturation of results or exhaustiveness because of the small number of interviewees, the 20 in-depth interviews conducted with young adults and consolidated through eighteen cross-interviews with some of their relatives provide interesting and sufficiently well-founded trends. Indeed, the richness of these in-depth interviews allows empirically applying the conceptual framework of social practices theories with precision in order to understand the importance of each practice component in the persistence or lack of persistence of sustainable practices during the holidays. In addition, crossing these first interviews with those of their parents, partners and/or siblings strongly consolidates the data by qualifying them, a richness that would never have been obtained without this method.
The first part of the results demonstrates a form of heterogeneity both in the adoption of sustainable practices in daily life as well as in their persistence during the holidays. Indeed, in everyday life, those who are vegetarians are not especially those who do not use the car as their main means of transport, while commuters are not necessarily attentive to the organic and local quality of their food. In addition, the results showed that the sustainable practices adopted on a daily basis did not persist especially during the holidays: some daily public transport users took the car to reach their holiday destination while some vegetarians ate meat during holidays.
These observations can be related to the concept of "compartmentalisation" defined by Halkier [74]. Based on Iversen's work [75], Halkier defines compartmentalisation as the way in which "reflected and chosen consumption practices can become 'crowded out' by tangible routinization" [74] (p. 39). This concept is then reinvested by Bartiaux [76] and Bartiaux and Reátegui Salmón [33] to express the idea that certain "green" practices can be adopted in some areas of consumption (e.g., food) and not in others (e.g., mobility). They explain that "eclecticism seems to be the norm and that 'green' considerations, if any, do not transmigrate among all practices" [33] (p. 476).
This contribution makes it possible to deepen this concept via a distinction between different forms of compartmentalisation: inter-thematic compartmentalisation, intra-thematic compartmentalisation and periodic compartmentalisation. The inter-thematic compartmentalisation is the adoption of "green" practices in some but not all consumption areas. Indeed, compartmentalisation occurs from one routine to another: sometimes the "green" focus is placed on food, sometimes on mobility but no regularity can be observed within the different consumption routines whose combination appears to be unique. An illustration of this inter-compartmentalisation is that among the young adults interviewed, some are attentive to eating organic, local and seasonal products but drive more than 100 km per day alone in their car.
The second type of compartmentalisation that I have observed is between two practices belonging to the same area of consumption. The adoption of eco-consumption practices is therefore not done in a homogeneous way, even within the same area. On the contrary, sustainable practices appear in a dispersed way within the same area of consumption. An example of intra-compartmentalisation is to fly to a rather close holiday destination (let's say a few hundred kilometres) and then use public transport once on-site.
Finally, I call a third form of observed compartmentalisation as "periodic". This form of compartmentalisation takes place only at certain times or during certain events. Here, the idea is that certain periods or certain events (a party with friends, Christmas, or holidays...) engender compartmentalisation. All the discrepancies between more sustainable practices of daily life and those of holidays are typical examples of periodic compartmentalisation.
These three types of compartmentalisation make it possible to answer the first question of this article: very few sustainable daily practices persist during the holidays. These observations can be characterized as periodic compartmentalisation in the sense that "green" practices are put in brackets for a specific period of time. However, at least one interviewee was enrolled in a vegetarian food practice during and after her long stay in Malaysia, even though she was not previously a vegetarian.
The second part of this contribution used an empirical application of the different components of practice developed by Schatzki [14] and Reckwitz [15] to show that the non-adoption (and even the non-persistence) of sustainable practices does not result from an oversight, or a lack of will or determination of practitioners. These sections showed the need to take into account the different dimensions allowing the adoption of a "greener" practice underlining the importance of each component of the practice. Indeed, material structures, routines, teleoaffective structures, and institutional dimensions must be considered as a whole constituting the practice, each component playing a role in the persistence, the transformation or the abandonment of sustainable practices. All of these components are required for the practice to take place. In this sense, the use of theories of social practices to study sustainable tourism through daily practices has proved to be relevant: the importance of each of the four components of the practice has been empirically demonstrated for understanding the adoption, persistence, or abandonment of sustainable practices.
Nevertheless, the last subsection has also shown one of the limitations of current theories of social practices. Indeed, it was observed that relatives also have an impact in the persistence or in the abandonment of practices. The section devoted to relatives highlighted that compromises and negotiations have to be made concerning whether the destination, the mode of transport or the food. This dimension remains insufficiently considered in theories of social practices (except in the work of Bartiaux and Reátegui Salmón).
Obviously, these initial reflections open up new avenues for reflection. From a theoretical point of view, a general reflection on the development of a definition of sustainable practice would be an important step forward in the field. On the other hand, future lines of research are also emerging, in particular by completely reversing the research question: are some more sustainable practices adopted during holidays? And if so, do they persist on a daily basis? In the light of the results relating to periodic compartmentalization, how can we envisage the career of practice? To what extent can it be fragmented? Are there other situations where sustainable practices are put in brackets?
Finally, this article has demonstrated that sustainable tourism is not limited to the material structures and other offers proposed by tourism professionals. On the contrary, sustainable tourism is also embodied in everyday practices: eating, travelling, grocery shopping, etc. However, these dimensions remain under-exploited in the area of sustainable tourism and the ambition of this article was to underline the relevance of deepening these questions especially since it was shown that some sustainable daily practices did not persist during the holidays. Sustainable tourism therefore concerns everybody-travel professionals, policy makers, consumers, governments, etc.-and it is played out at all levels. To encourage it, no component and no contributor should be omitted.